This was the first time they had seen each other since Leandro's exclusive chat with Reveal, where he describes Katie as being "empty inside" and a "WAG wannabe".
Katie - aka Jordan - arrived at the launch night in Hyde Park first with her daughter Princess Tiaami and several pals, and Leandro turned up shortly after.
The former couple then had a very awkward encounter when Katie walked into the VIP bar while Leandro was in there enjoying a drink with friends.
>Read our Leandro exclusive: "Katie Price will never get over Peter Andre
An eyewitness tells Reveal: "Katie knew Leandro was there and shot him a really frosty look when she walked in the bar.
"Everyone was waiting for her to confront him, but surprisingly she decided to keep her distance and went and sat at a table in the corner.
"Katie kept looking over at Leandro though. You could have cut the air with a knife."
Although he didn't seem bothered by his run-in, Leandro soon made a swift exit. After trying out the rides, the Argentinian model headed to Mediterranean fish restaurant, Disiac, in nearby Soho for a later dinner with friends.
Katie, meanwhile, took to Twitter after a fan sent her a message asking if she had been begging Leandro to take her back.
"Absolutely not," she replied.
Watch our exclusive video interview with Leandro below and see him describe how Katie has few friends.
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